Oscillatory behavior of chromospheric fine structures in a network and a semi-active regions

Abstract

In the present work, we study the periodicities of oscillations in dark fine structures using observations of a network and a semi-active region close to the solar disk center. We simultaneously obtained spatially high resolution time series of white light images and narrow band images in the H$\alpha$ line using the 2D G\"ottingen spectrometer, which were based on two Fabry-Perot interferometers and mounted in the VTT/Observatorio del Teide/Tenerife. During the observations, the H$\alpha$ line was scanned at 18 wavelength positions with steps of 125 m\AA. We computed series of Doppler and intensity images by subtraction and addition of the H$\alpha$ $\pm$ 0.3 \AA\ and $\pm$ 0.7 \AA\ pairs, sampling the upper chromosphere and the upper photosphere, respectively. Then we obtained power, coherence and phase difference spectra by performing a wavelet analysis to the Doppler fluctuations. Here, we present comparative results of oscillatory properties of dark fine structures seen in a network and a semi-active region.Comment: 8 pages, 5 figures, accepted for publication in MNRA